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Heat treating discoloration
- Thread starter Brickcart
- Start date
- Joined
- Aug 20, 2022
- Messages
- 1,234
You have three topics here
Discoloration
Heat Treat
Stainless
I'm sure this will be moved to the forum where folks can advise you.
Discoloration
Heat Treat
Stainless
I'm sure this will be moved to the forum where folks can advise you.
am I on the wrong forum for this question ?
Stacy E. Apelt - Bladesmith
ilmarinen - MODERATOR
Moderator
Knifemaker / Craftsman / Service Provider
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- Aug 20, 2004
- Messages
- 37,723
Welcome Brickcart. Fill out your profile with your location and some info about yourself. It helps us give better answers.
The discoloration is only a surface oxide. It is removed in the post-HT grinding and finishing.
If it is deeper than that you may have a foil pouch not sealed properly.
You will find suggestions with putting a piece of paper or charcoal in the pouch. This is not done much anymore. It really doesn't do much. Double sealing the seams and rolling or hammering them tight with a wooden or nylon mallet works best.
There is a tendency for new knifemakers to think that the blade comes out of HT ready for a handle and sharpening. This is not true. The surface of the blade needs to be sanded down at least .005" to remove the "skin" of carbon depleted metal. It can be deeper than that in some cases. Many makers doing stainless steels now only profile the blade and then do HT. The bevels and plunge are ground after HT. A water mist system like the Kool-Mist setup is very helpful here, but you can do it by the grind-and-dip method.
Tell us about what steel you are using, your HT method details, and maybe post a photo of the discoloration you are referring to. That will help us determine what the issue is.
The discoloration is only a surface oxide. It is removed in the post-HT grinding and finishing.
If it is deeper than that you may have a foil pouch not sealed properly.
You will find suggestions with putting a piece of paper or charcoal in the pouch. This is not done much anymore. It really doesn't do much. Double sealing the seams and rolling or hammering them tight with a wooden or nylon mallet works best.
There is a tendency for new knifemakers to think that the blade comes out of HT ready for a handle and sharpening. This is not true. The surface of the blade needs to be sanded down at least .005" to remove the "skin" of carbon depleted metal. It can be deeper than that in some cases. Many makers doing stainless steels now only profile the blade and then do HT. The bevels and plunge are ground after HT. A water mist system like the Kool-Mist setup is very helpful here, but you can do it by the grind-and-dip method.
Tell us about what steel you are using, your HT method details, and maybe post a photo of the discoloration you are referring to. That will help us determine what the issue is.
JV Knives
Knifemaker / Craftsman / Service Provider
- Joined
- Jun 11, 2008
- Messages
- 1,342
B
Brickcart
Even with properly sealed pieces, you are going to eliminate the decarb impurities from the air, but the heat lines showing on the surface are totally normal. Please see below AEBL coming out of the packets. These come off easily in grind...unlike the burnt marshmallow effect of no packet! 
Notice how the unopened packet is drawn in like vacuum forming. This is when you have the seals hammered in correctly and block out external air. Are your packets looking like this, or ballooning up?
![IMG_2493[1].JPG](https://www.bladeforums.com/data/attachments/2002/2002769-8bd69150b1582fcaeca625e97a0074b3.jpg?hash=i9aRULFYL8 "IMG_2493[1].JPG")
Notice how the unopened packet is drawn in like vacuum forming. This is when you have the seals hammered in correctly and block out external air. Are your packets looking like this, or ballooning up?